Why Not Defragment Your Hard Disk Today?

Does your computer run as fast as it did the first day you brought it home from the
store? If you have been using it for several months or more, more than likely it has
begun to operate more slowly. There can be many causes for this, for example too many
processes running simultaneously, or invasion by spy ware or a virus. But the most
common cause is a fragmented hard disk.

First let’s understand what disk fragmentation is. A hard disk is constructed of
disk shaped platters with a magnetizeable coating their surface. As the platters spin
at a very high speed, tiny coils skim over the surface of each platter reading and
writing data. Each of the circular paths on a platter is called a “track”. An arch
section of a track is called a “sector”.

When a file is written, it is written to the first unused sector on the disk. When
your computer was new and all the software was consecutively written to the hard drive,
your hard drive looked similar to that shown below.

While using your computer, you delete file A, write file D, and Enlarge file C and
File A. This causes the data on your hard disk to be arranged as shown below.

Now you can see that in order to read file A from the hard disk, the read coil has
to search and skip for the scattered bits of the file. As files are written, deleted
and rewritten in different size, unused blocks of space become discontiguous. Parts
of individual files become scattered across the disk. Your computer takes longer to
load applications and data files.